1. Field Of The Invention
This invention relates to a loader and an unloader for a tire vulcanizer. Stated more specifically, this invention relates to a compact and economical loader for a tire vulcanizer for carrying in untreated tires to a mold with high precision, when there are two or more mold lines, and different sizes of untreated tires must be conveyed to the mold. This invention further relates to a compact and economical unloader for a tire vulcanizer for carrying out treated tires from the mold with high precision.
2. Description Of The Related Art
Carry-in or conveyance of untreated tires to a tire vulcanizer is generally performed for two mold lines on the left and right. Therefore, a system is generally utilized in which two units on the left and right simultaneously raise and lower a loader for carry-in of untreated tires from a supply unit to the vulcanizer mold, and an unloader for carry-out of the vulcanized tire from the vulcanizer mold. Further there are also cases where a mechanism is provided for adjusting the height of a tire grip in order to match the height of the untreated tires being supplied, in the event the tire sizes of the two lines differ. There is also tire vulcanizing equipment of a multi-system type utilizing numerous mold lines, not being limited to the above two mold line system, and provided with tire grip in each loader and unloader having a height adjusting mechanism.
The height adjusting mechanism on these types of tire grips (especially in the loader) utilized in conventional equipment are broadly classified into the following two types. One type provides a screw structure in the center of the tire grip, and when this screw is turned, the tire grip and boom rise and lower, relative to a frame (see Japanese Patent Publication No. HEI 6-51295). Another type of tire grip is mounted at the tip of a swivel boom capable of freely moving up and down, and has a screw structure provided in the swivel axis of the boom. By turning this screw to raise and lower the boom, the tire grip is made to raise and lower as an integral part of the boom (see Japanese Patent Publication No. SHO 46-24773).
However both these conventional devices have problems. The type with a direct screw structure provided in the center of the tire grip, does have the advantage that the center of the untreated tire can be made to fit with good precision in the center of the mold of the vulcanizer. However, in the initial molding (hereafter "shaping") of the tire, the tip of the center mechanism of a telescoping bladder must pass through a hole of limited dimensions from the lower center surface of the tire grip, from bottom to top. Unfortunately, since the previously mentioned screw structure is located at the center of the tire grip, this kind of center mechanism (telescoping bladder) is blocked and cannot pass through.
A plurality of tire grip paddles (hereafter "paddles"), located in the lower part of the tire grip and being expandable/contractible in the horizontal and radial direction of the equipment, has long legged structures, and they were utilized to form an extra empty space near the center of the lower side of the tire grip so that the shaping could be performed without damage. However, in order to maintain high precision for insertion in the center position of the mold, the strength of each paddle had to be increased according to the length of the long legged structure. This necessity caused the problem that the tire grip had to be made into a larger-scale unit.
On the other hand, in the type having the screw structure provided in the swivel axis of the boom, the tip of a mechanism of the bladder is designed to pierce a hole at the center of the bladder in the lower central surface of the tire grip. This type of tire grip is compact and capable of performing shaping without using the long legged tire grip paddles. However, unlike the conventional example first mentioned above, this type has poor precision because there is a considerable distance between the center of the tire grip and the swivel axis of the boom. Therefore only a slight error in the screw feed of the boom swivel axis is magnified according to the length of the boom at the center of the tire grip, finally causing an error too large to be ignored. This makes it difficult for the untreated tire center to be mounted on the mold center in the vulcanizer, making improvements in product precision unlikely.
Another method uses a direct-action hydraulic cylinder linked to the boom without using a screw structure for raising and lowering the boom as was done in the second conventional example. This method regulates raising and lowering of the boom by controlling a hydraulic cylinder operation with optional position settings by means of control mechanisms and distance sensors such as rotary encoders. However the structure of this method is not only overly complicated but impractical since the cost of the loader and unloader is too high. The above listed problems are not limited to a loader but also occur in an unloader.